just turn the data/wifi off when you lock the screen.
that takes care of the whole problem.
Personally, I use MacroDroid to turn off the internet when the screen locks.
Likewise, MacroDroid turns the internet on when the screen unlocks.
If my phone is idle, it can go a full day on less than 5% battery use.
I just stuck it on the wireless charger a bit ago at 60% after 3-1/2 days of use. That included a lot of phone calls, texting, videos, newspaper surfing, etc.....
But, when I press the Power Button, my phone goes into a super deep sleep.... just the way I like it.
I always leave Sync OFF. Have no use for it at all.
if anyone is interested, I will email the macro list to import into MacroDroid. Some have asked me for that already and I don't mind doing it.
Just use a PM, don't put your email in the open forum please.